Wet treatment of raw bast fibers



Patented Nov. 14, 1939 PATENT orncs 2,180,687 WET TREATMENT OF RAW BAST FIBERS Helmuth Korte, Frankfort-on-the-Main, Germany, assignor to I. G.-Farbenindustrle Aktiengeselischaft, Frankfort-on-the-Main,

Germany No Drawing. Application October 20, 1936, Serial No. 106,693. In Germany October 24, 1935 Claims.

The present invention relates to a wet treatment of bast fibers, more particularly of raw bast fibers.

It has hitherto been usual to mechanically clean 5 bast fiber roving of retted material which has been pre-treated on suitable machines and to bleach the material in the form of threads or.

yarn.

Now I have found that raw, that is non-retted bast fibers, for instance bast of flax or hemp from which the woody matter has been removed as far as possible by a suitable decorticator i. e. only by mechanical treatment, may be used as starting material. From this non-rotted raw bast there is, first formed a roving which is brought into the form of cross wound bobbins instead of into the form of the roving bobbins hitherto used. These cross wound bobbins are subjected to a wet treatment, e. g. to a chemical decomposing process which may, for instance, consist in boiling the roving with alkali lye and then causing acid hypochlorite solutions or chlorine water solutions to act thereon. The roving is then treated, while hot, with acids or it is boiled with acid, neutral or alkaline sulfite solutions or alkali lyes.

Alternately the material may first be treated with acid and then, if desired without an intermediate rinsing, with the acidified solutions oi. hypochlorites or sulfites of the alkali metals or alkaline earth metals containing free mineral acids or chlorine water or a sulfite. The chlorinating solution may be prepared, for instance, after a sufiicient action of the acid by introducing chlorine. By this method of treatment the raw bast fibers are not only opened up, but at the same time cleaned, i. e. the woody constituents and the substances accompanying the cellulose (chafl as well as lignin and pectin substances) are for the most part removed.

The quite clean thread thus obtained may then be made lighter in color by any known bleaching process. It can readily be further treated by various known methods and then be dyed.

If the above described treatment of the roving on cross wound bobbins with acid hypochlorite solutions or chlorine water solutions and strongly alkaline lyes is repeated until all the substances that accompany the raw bast fibers are removed,

there is obtained a thread of a' particularly soit character which may also be spun on cotton spinning machines.

It is also possible to produce mixed threads Raw bast fibers oi flax in the form of roving -on cross wound bobbins are boiled for 1-2 hours with a liquor containing 24 grams of caustic soda per liter. After the material has been rinsed it is treated with a chlorinating solution, for in- 5 stance a solution of hypochlorous acid which has been adjusted to a content of about 5-6 grams of active chlorine per liter and pH 5. After the usual rinsing and dechlorination the material is boiled for about 2 hours with a solution contain- 10 ing 2-4 grams of caustic soda per liter. The material is then bleached with a solution containing about 1.5 per cent. of active chlorine (calculated upon the weight of the material). There is obtained an entirely pure white thread which is 15 free from chat! and is excellently suitable for spinning.

I claim:

1. The process of producing fibers which comprises subjecting raw bast fibers to mechanical 20 treatment in a decorticator to remove woody matter therefrom, and subjecting the so treated fibers in the form of roving on cross wound bobbins to a wet treatment adapted to improve the physical properties of the fibers.

2. The process of producing bast fibers which 25 comprises subjecting raw'bast fibers to mechanical treatment in a decorticator to remove woody matter therefrom, and subjecting the so treated fibers in the form of roving on cross wound bobbins to a treatment adapted to decompose incrusting matter.

3. The process of producing bast fibers which comprises subjecting raw bast fibers to mechanical treatment in a decorticator to remove woody matter therefrom, and subjecting the so treated 35 fibers to a treatment adapted to decompose incrusting matter and to a cleaning action while in the form of roving on cross wound bobbins.

4. The process of producing bast fibers which comprises subjecting raw bast fibers to mechanical treatment in a decorticator to remove woody matter therefrom,and subjecting'the so treated fibers to -a treatment adapted to decompose incrusting matter, a cleaning action and a bleaching treatment while in the form of roving on cross wound bobbins.

5. The process of producing bast fibers which comprises subjecting raw bast fibers to mechanical treatment in a decorticator to remove woody mattertherefrom, and subjecting the so treated 50 BEIMU'I'H KORTE. 

